Method of making wrought-metal articles



Patented Apr; 30,1929. i p 1,711,000 v UNITED STATES PATENT OFFICE.

CHARLES 3. SHORT, OF DAYTON, OHIO, ASSIGNOR TO GENERAL MOTORS RESEARCH CORPORATION, OF DAYTON, OHIO, A CORPORATION OF DELAWARE' METHOD OF MAKING WBOUGHT-IdETAL ARTICLES. No Drawing. Application filed July 2, 1925. .Strlal Ko. 41,114.f

This invention relates to the manufacture to the metal superior to that incident to un- '55 of metallic objects by a combination of castfinished castings. 7 ing and forging, or other similar metal-work- The casting operation ma be performed ing steps. By metal-working is meant such preferably in chill or die molds. These molds operations as impart to metal the characterismay be of iron, copper or other metal suitable tics of so-called wrought metal, that is, opfor die molds.- Metallic or die molds conerations that deform the metal or cause it to duct heat from the casting quickly and, therefiow more or less, such as rolling, hammer or fore, cause the casting to set quickly and enpress forging, drawing, extruding or the like. able it to be removed quickly. Quick set- 10 It is an object of the invention to produce ting and removal of the casting reduces the metallic articles having the desirable prolikelihood of deformation or flaws in the cast perties of wrought metal, without subjecting due to shrinking in the molds. By using ing the metal to the extremes of distortion metal molds which cool the casting rapidly, and molecular flow incident to the forging certain metallic compositions with a suitable 15 of articles to final form from ingot, billet proportion of silicon ma be used as the castor bar. In the usual practice of making ing metal, whereby to 0 tain a more ductile wrought metal articles, the extent of flow or malleable product than could be obtained is considerable and the direction of flow is by casting in a sand mold. not as a rule controllable. It follows that The method under consideration has been 20 where very considerable changes of sizeand found of great utility in making articles of form are produced by forging, the metal certain light alloys such as magnesium and flows in various directions and some parts aluminum alloys. F or example, an aluminum flow more than others. In consequence the alloy, high in silicon may be first cast in an articles are apt to be weaker in some parts oversize metal mold that is an a proximate than in others. The weaknesses due to excounterpart of the articletobe ma e, removed cessive flow are more apt to occur in some therefrom soon after it has set and before it kinds of metal than in others. It is particuhas lost so much heat as to cause it to shrink larly desirable not to work excessively, for to any great extent, and may then be comexample, aluminum and certain other alloys. pacted to final size between forging dies.

30 A further defect due to excessive Working by The silicon content should be sufficient to pressure is the piping or radishing flaw produce an alloy that is hot short within 35 that frequently develops in the interior of the narrowest possible range of temperature, wrought metal articles, which is wholly conand may be cast to advantage within chilled cealed. molds.

35 According to this invention, when it is dc- After removal from the mold the blank sired to produce any given metal article, a may be forged while still hotfrom the castmold is made, which is approximately a couning operation, provided the casting is of such terpart of the desired article, but is somecomposition as will stand forging at that what larger, and a blank is cast in this mold temperature. Castings made from com osi- 4Q by pouring into it molten metal of the kind tlons may be forged while the are sti hot desired. .The oversize blank thus formed may from the casting operation. thers may be '95 I now .be reduced in order to form the finished forged cold. Still others, among them the article by any process of working suited to aluminum alloy referred to, may require for the particular blank and article. The blank best results a reheating, while some may re- 45 may, for example, be compressed between qulreaheat-treatment after forging. forging or rolling dies of a size and contour .The special utllity of the described method to reduce the blank to final size. The workapplied to manufacture of'articles from. light ing pressure thus applied will cause some alloys; or homogeneous mixtures of metals, flow of metal, suflicient to close up interstices, lies in the fact that-it avoids certain defects 50 such as blow holes, and fill small cavities reof prior processes. In these mixtures or als'ulting from failure of the meta to comloys, as in many others in which the different pletely fill or flow to all parts of the mold. ingredients have rather widely separated; It will endow the article with the desirable melting points, there is a tendency for the qualities of wrought mctal and impart a finish ingredients to separate when a cast ng is set- 2 1,711,ooo

ting or freezing from a molten state. The

- sive working process being subject to 'thc other detects already mentioned.

By casting, according to this'method. alloys of the type mentioned in metal molds, the casting cools so quickly that there is insufficient time for the ingredients to segregate materially. By reason of the rapid setting of the casting. it may be removed from the mold before sutlicient shrinkage occurs to tear or weaken the metal in the mold. Thisis a very important circumstance in casting articles, which, like connecting .rods, have separated enlargements connected by a part of smaller cross-section. In castings of this form theenlarged portions, being anchored:

in the mold, are apt to tear partly away from the. smaller portions during shrinkage if left in the mold, thus developing av serious flaw. By the method of this invention, flaws of the kind described are avoided, and superior castings obtained.

i It the casting, made and removed as described, is then worked under pressure all over sons to slightly reduce its cross-sectional area, without; excessive flow, the article may be perfected in finish, the metal compacted, interior holes closed and external cavities filled by slight flow of the metal. Thus the described casting has imparted to it the desirable qualities of wrought metal free of the defects incident to manufacture wholly by pressure working.

By this method, metal articles of rather sli ht malleability, which cannot be successfully wrought entirely by forging, may be i ananufactured and will be found to possess i to a degree the qualities of wrought metal articleswithout their defects.

Immziking, for example, a light alloy connecting rod by this method, a die or metallic mold will be made which is approximately a counterpart of the finished article desired but slightly larger. The alloy will then be 'poured in a molten condition into the die or mold. As soon as the blank thus cast, has set, the die or mold will be opened and the east blank removed. If the heat in the blank is above that at which the material of the blank is hot-short it should immediately be forged to size, as in forging dies which are a counterpart in size of the desired finished arti'ele. Otherwise. the blank may be reheated to the requisite temperature and then wrought.

to size. A heat-treatment may be given the finished article after forging, it the propertiesof the particular alloy used render it desirable.

In casting connecting rods, it is desirable to provide suitable cores or bosses withinthc moldto provide the necessary recesses for the crank and Wrist pin in order to avoid piping, and to thereafter forgo the casting with metallic plugs inserted in the recesses.-

lVhile the form of embodiment of the invention as herein disclosed, constitutes a preferred form, it is to he understood that other forms might be adopted, all coming within the scope of the claims which follow.

\Vhat is claimed is as follows:

1. A method of makmgmetallic articles. which consists in casting a blank in a chill mold that is approximately a counterpart of but somewhat larger than the desired article, removing the cast blank and reducing it to final size by working itunder pressure.

2. The method of making metallic articles, which consists in casting a blank in a mold that is approximately a counterpart of but slightl '-larger than the desired article, re-

"movingthe cast blank, and reducing it to final size by working it under pressure while still hot from the casting operation.

3. A method of making metallic articles. which consists in casting a blank in a chill mold that is approximately a counterpart of but; somewhat larger than the desired article, removing the east blank from the mold before it has cooled enough to shrink materially,

and reducing said blank to final size by working it under pressure.

4. The method of making articles from alloys containing metallic constituents of substantially (lifi'erent melting points,'said constituents tending to separate from a molten mixture thereof when cooling. which consists in pouring molten alloy metal of the kinddescribed into a chill mold that is approximately a counterpart of but somewhat larger than the desired article, said mold being of sutlici nt conductivity to cause the cast blank to set before separation can take place, removing the cast blank and reducing it to final size by working it under pressure.

5. The method of making articles from alloys containing metallic constituents of substantially difi'erentmelting points, said constituents tending to separate from a molten mixture thereof when cooling, which consists in pouring molten alloy metal of the kind de-v and reduc- 6. The method of making articles from alloys containing metallic constituents of substantially different melting points, said constituents tending to separate from a molten mixture thereof when cooling, which consists in pouring molten alloy metal of the kind described into a chill mold that is approximately a counterpart of but somewhat larger than the desired article, said mold being of sutlicient conductivity to cause the cast blank to set before separation can take place, removing the. cast blank after it has set and before it has cooled enough to shrink materially, and reducing it to final size by working it under pressure.

7. The method of making articles from alloys containing metallic constituents of substantially differentmelting points, said constituents tending to separate from a molten mixture thereof when cooling, which consists in pouring molten alloy metal of the kind described into a chill mold that is approximately a counterpart of but somewhat larger than the desired article, said mold being of suflicient conductivity to cause the cast blank to set before separation can take place removing the cast blank from the mold, and reducing it to final size by working it under pressure at a temperature above that at which the metal of the casting is hot-short.

8. The method of making articles from an alloy of aluminum containing silicon, which consists in pouring said alloy in molten condition into a chill mold that is approximately a counterpart of but somewhat larger than the desired article, removing the cast blank from the mold, and reducing it to final size by working it under pressure.

9. The method of making articles from an alloy of aluminum containing silicon, which consists in pouring said alloy in molten condition into a chill mold that is approximately a counterpart of but somewhat larger than the desired article. removing the cast blank from the mold after it has set and before it has cooled enough to shrink materially, and reducing it to final size by working it under pressure.

10. The method of making articles from an 'alloy of aluminum containing silicon, which consists in pouring said alloy in molten condition into a chill mold that is approximately a counterpart of but somewhat larger than the desired article, removing the cast blank from the mold, and reducing it to final size by working it under pressure at' a temperature above that at which the metal of the casting is hot-short.

11. The method of making articles from an alloy of aluminum containing silicon, which consists in pouring said alloy in a molten condition into a chill mold that is approximately a counterpart of but somewhat larger than the desired article, removing the cast blank from the mold after it has set and before it has cooled enough to shrink materially, and reducing to final size by compressing it in forging dies which are a counterpart of the desired article.

In testimony whereof I hereunto atlix my signature.

CHARLES R. SHORT. 

